Membrane　distillation　(MD)　is　considered　as　a　promising　technology　for　reverse　osmosis　(RO)　brine　treatment,　but　application　of　MD　is　significantly　hampered　by　gypsum　scaling　and　subsequent　membrane　wetting.　As　antiscalants　are　widely　used　in　RO　desalination,　it　is　of　interest　to　understand　effects　of　residual　antiscalants　on　membrane　scaling　during　RO　brine　treatment　using　MD.　In　this　work,　MDC220,　PTP-0100　and　SHMP　were　adopted　to　study　effects　of　residual　antiscalants　on　water　vapor　flux,　distillate　conductivity　and　scale　growth　using　a　direct　contact　membrane　distillation　(DCMD)　device.　Feed　temperature　and　antiscalant　dose　were　investigated　in　ranges　of　40-60　degrees　C　and　0-10　mg　L-1,　respectively.　Moreover,　morphological　characterization　of　scale　layers　in　the　presence　of　antiscalants　were　performed　using　a　field　emission　scanning　electron　microscopy.　The　results　show　that　all　the　antiscalants　neither　decreased　feed　surface　tension　nor　worsened　distillate　quality.　The　presence　of　antiscalants　effectively　retarded　flux　decline　and　distillate　conductivity　increase;　SHMP　and　MDC220　outperformed　PTP-0100　in　restricting　gypsum　scaling.　The　performance　of　antiscalants　was　temperature　dependent,　and　increased　feed　temperature　adversely　affected　scaling　inhibition　performance.　The　dose　of　antiscalants　played　a　significant　role　in　gypsum　scaling　restriction　and　the　inhibition　performance　was　superb　at　a　MDC220　dose　not　less　than　5　mg　L-1.